The invention relates to a load lifting apparatus for a helicopter. The invention further relates to a helicopter comprising a load lifting apparatus. In particular, the invention relates to a type of load lifting apparatus comprising a cable, of which a supply length is present in a cable store, wherein the cable, on the one hand, is secured on the helicopter and, on the other hand, has a free end, and a load-bearing element, which is arranged on the cable and on which a load which is to be raised can be secured, wherein the cable can be removed from the cable store in order to lower the load-bearing element downwards from the helicopter, wherein the cable, as the load-bearing element is being lowered or pulled upwards, acts at a force-introduction location on the helicopter.
A load lifting apparatus of the type mentioned before is used, in particular, in rescue helicopters for rescuing accident victims. Such rescue helicopters are often used for sea and mountain rescue.
A load lifting apparatus which is known from DE 33 23 513 A1 has a cable store in the form of a winch, on which a supply length of cable is stored. The winch in this document is mounted on the ceiling in the cabin of the helicopter. From the winch, the cable is guided outwards out of the cabin of the helicopter along an extension arm, wherein the end of the extension arm has arranged on it a deflecting roller, via which the cable then leads away downwards under the force of gravity. In this case, the deflecting roller arranged at the end of the extension arm constitutes the force-introduction location at which the cable acts on the helicopter as the load is being lowered or pulled upwards.
The load-bearing element of the known load lifting apparatus is de-signed as a load hook which is fastened at the free end of the cable. The rescue harness can then be suspended from the load hook in the event of rescuing an accident victim.
Rescuing people using a helicopter which is equipped with a load lifting apparatus like the known load lifting apparatus gives rise to the following problems. Since the rescue takes place from the air, and the cable is correspondingly lowered to the rescue site in order to pick up the person who is to be rescued, the load suspended from the load-bearing element is subjected to the downwardly directed downwash from the helicopter rotor. The downwash, in addition to a downwardly directed component, also has a pronounced rotary component in the direction of rotation of the rotor. This rotary component is sufficient in order for the load suspended from the cable to be set in rotation about the cable axis. In the event of a person who is to be rescued being suspended from the cable, the person is correspondingly set in rotation about the cable axis, wherein rotational speeds of approximately two to three revolutions per second are reached. The centrifugal forces acting on the person here are so pronounced that, while they may perhaps yet be withstood by a healthy individual, they will not be withstood by somebody who is weak, for example somebody who has been injured, and is to be rescued from an accident site. This problem arises both for picking up the load and for setting down a load on the ground, and in particular when the helicopter, rather than flying forwards, is hovering in the air during these procedures, whereas the rotary downwash is less obvious when the helicopter is flying forwards. The attempt is therefore often made to start forward flying immediately after the load has been picked up or, conversely, to set down the load while flying forwards. However, this procedure is not readily possible on difficult terrain, in particular in mountainous terrain, for example if a person has to be rescued from a deep crevice.
Another possible way of avoiding rotation of the load suspended from the cable consists in an auxiliary on the ground holding an anti-rotation line, which is fastened on the load harness, under tensioning at an angle of 45° to 90° to the cable of the load lifting apparatus, rotation of the load likewise being avoided as a result. However, this procedure is also problematic in difficult terrain, and terrain which is difficult to access, in particular for rescuing people at sea, where it is difficult, if not impossible, to set down the auxiliary. There is also the disadvantage that more personnel and equipment is required for a rescue attempt.
There is therefore a need for a load lifting apparatus for a helicopter which avoids the aforementioned problems.
Load lifting apparatus which use multi-cable systems are also known. Thus, for example, DE 2 021 040 A1 describes a load lifting apparatus in which a cable is attached at each corner of the load and the cables are wound up by individual winches on board the helicopter. Such a load lifting apparatus, in addition to being of complex design, is also disadvantageous in the event where an emergency situation requires the load to be jettisoned, for which reason all four cables then have to be cut individually. In order to avoid this problem, the document proposes fastening, on the load cable fastened on the helicopter, a load beam, from which, in turn, a plurality of cables extend downwards.
Further such complex-design load lifting apparatus for helicopters are described in DE 1 253 058 A1, DE 1 106 605 A1, DE 1 456 092 and DE 2 210 084.